Effect of air annealing on photo detecting properties of S-SILAR deposited SnS films

The well-known SILAR technique has been widely used to fabricate cost effective and durable photodetectors. From the past few decades, tin sulfide is known as a promising material for wide range photodetectors. In the present case tin sulfide films were deposited on borosilicate glass substrates by simplified SILAR technique without any complexing agents. Tin chloride and sodium sulphide were used as cationic and anionic precursors. The structural and optical properties of as deposited and annealed thin films were studied in detail. Both as deposited and annealed tin sulfide thin films showed orthorhombic crystal structure with preferred orientation along (0 4 0) plane. Both as deposited and annealed films showed significance absorption in visible and NIR region with 75% transmission. The absorption coefficient was of the order of 10^-4cm^-1. The fabricated visible range photodetector with silver contacts showed significant enhancement in the photo response upon annealing. The response current and specific detectivity was found to be 30nA and 0.3 × 10⁶jones. Annealed SnS films showed considerable speed of response with 15.71 s rise time and 10.29 s decay time, that can be used for visible light photodetector applications.